US3033998A - Pulse former - Google Patents

Pulse former Download PDF

Info

Publication number
US3033998A
US3033998A US826854A US82685459A US3033998A US 3033998 A US3033998 A US 3033998A US 826854 A US826854 A US 826854A US 82685459 A US82685459 A US 82685459A US 3033998 A US3033998 A US 3033998A
Authority
US
United States
Prior art keywords
transistor
circuit
current
impedance state
voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US826854A
Inventor
Nellis William Merton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
American Monarch Corp
Original Assignee
American Monarch Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by American Monarch Corp filed Critical American Monarch Corp
Priority to US826854A priority Critical patent/US3033998A/en
Application granted granted Critical
Publication of US3033998A publication Critical patent/US3033998A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/26—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback
    • H03K3/28—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback
    • H03K3/281—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback using at least two transistors so coupled that the input of one is derived from the output of another, e.g. multivibrator
    • H03K3/284—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of bipolar transistors with internal or external positive feedback using means other than a transformer for feedback using at least two transistors so coupled that the input of one is derived from the output of another, e.g. multivibrator monostable

Definitions

  • This invention relates to a bistable electrical circuit for forming an electrical impulse of a predetermined duration in response to a signal of shorter duration.
  • pulse formers have been utilized to provide such a function including the well known monostable multivibrator in which one of the two non-linear discharge elements therein, such as a transistor, is biased to non-conduction or a high impedance state while the other element is biased to a highly conductive or a low impedance state.
  • the circuit is responsive to an input signal of short duration to switch the conduction or impedance states for a predetermined time, after which the multivibrator automatically reswitches to the initial state.
  • This invention obviates the above objections by providing a pulse former wherein both non-linear discharge elements are in high impedance state and both switch to a low impedance state for a predetermined time in response to an input signal of short duration.
  • the circuit is insensitive to extraneous electrical disturbances and provides rapid impedance switching from both high to low and low to high impedance states.
  • FIG. 1 is a schematic drawing of a circuit embodying this invention.
  • FIG. 2 illustrates typical wave forms associated with the FIG. 1 circuit.
  • the PNP transistor 10 With reference now to the drawing complementary ing material.
  • NPN transistor 12 in a high impedance state, i.e., at collector current cutolf, the PNP transistor 10 is also in a high impedance state.
  • the current drive to base 10B is provided from the resistances 14 and 16 formed junction 18 as determined by the impedance state of discharge element12.
  • element 12 When element 12 is in a high impedance state it is apparent that the battery B voltage is essentially applied to base 10B as well as emitter or high current electrode 10E providing no current through the base electrode.
  • Resistance 14 of small impedance is primarily provided to reduce the leakage current effect on the bistable circuit.
  • the base or control electrode 12B is connected to junction 20 between resistances 22 and 24 with resistance 22 being coupled to the transistor or discharge element 10 collector or high current electrode to complete a series connected bistable or latch circuit, as will become apparent.
  • a negative going signal 27 of short duration from the source 26 is applied to junction 18 and thus base 10B.
  • the input pulse voltage is developed across resistance 14 to make base 10B negative with respect to emitterjliiE.
  • Base drive current flows through the base electrode 10B making the transistor or element 10 conductive or tending toward a low impedance state as measured between the collector and emitter high current electrodes.
  • the change in impedance of the element 10 causes the junction 28 voltage to become somewhat positive with respect to the initial voltage thereon.
  • the voltage change is transferred through the timing capacitor 30 and re sistance 22 to the base electrode 12B.
  • the positive going transient voltage just described causes NPN transistor 12 to become slightly conductive tending toward a low impedance state which draws additional current through re; sistance 16 and thereby tending to make the voltage on termed the low impedance state.
  • the voltage on junction 18 is shown as wave 31 and the circuit remains in the low impedance state providing voltage pulse 32A across the load 32 and having an amplitude near the battery voltage potential.
  • the base drive current for NPN transistor 12 is provided through transistor 10, thence timing capacitor 30 and resistance 22. This small current is operative to charge capacitor 30 while the circuit low impedance elements permit a substantial current to flow through a load 32 from the transistor 10 and battery B.
  • the voltage across the timing capacitor 30 is shown by numeral 33 and when the capacitor is substantially charged as at 35 the base drive current for transistor 12 is decreased below the base current amplitude required for transistor 12 collector current saturation. This action reduces the current through the high current electrodes -12C and 12B and thus permits junction 18 voltage to move more positive to make transistor less conductive.
  • the regenerative loop again provides cumulative impedance switching action in that the positive going transient at junction 18 increases the impedance of transistor 19 causing the voltage at 28 to become less positive further reducing the base drive current to the transistor 12. Since this switching action is very rapid and the capacitor 30 has a charge thereacross as indicated in f circuit to extraneousrelectrical disturbances.
  • the capacitor 30 must now discharge through the load impedance 32 and the series connected resistances 22 and 24. Since this series circuit loop is a'relatively high impedance the discharge time may be greater than the duration of the formed pulse 32A across theload 32. The repetitive frequency at which the circuit can provide the desired pulses is in such a case limited by the discharge time of the capacitor 30.
  • a uni-directional conducting device or diode 36 is connected in parallel with the resistances 22 and 24 with its cathode electrode connected to the capacitor 7 39 to provide a lowered impedance discharge pathfor the capacitor rapidly placingthecapacitor in a discharged state. It is seen that with the two discharge elements in a high impedance state-the voltage across the capacitor 30 urges electrical curr'entto flow through load 32 and thence through diode 36 in the forward direction with the load32 absorbing most of the electric charge. Since the load 32 is preferably of low impedance, for example about 1000 ohms, the discharge time for the capacitor 30 is greatly: reduced as indicated by trailing edge 37 rather than the previous discharge voltage wave 37A through the high impedance resistances 22 and 24.
  • a silicon diode or uni directional current conducting device 38 with a small forward impedance is connected in the forward current conducting direction between emitter electrode 12B and the battery B negative or grounded terminal.
  • Resistance 40 connected to the battery positiveterminal provides a bias current through diode 38 making the emitter 12E at all times slightly positive with respect to ground potential.
  • This feature not only aids in driving the transistor 12 to a high impedance state but adds to the insensitivity of the Further circuit insensitivity to the disturbances may be provided by adding a filtercapacitor 42 between the transistor 10' collector electrode and ground. Since the filter 42 has a much larger. capacitive value than timingcapacitor 30,
  • Filter 42 is desirable when load 32 is a relay.
  • a pnlse former comprising first and second transistors of complementary types, a'supply voltage source having a grounded terminal anda second terminal connected to. the emitter ofthefirst transistor, a signal source for providing a pulse of short duration to the first transistor base for switching the circuit from a high to a low impedance state, a series connected capacitor and resistor connecting the first transistor collector and second transistor base together, a first resistor connecting the second transistor collector to the .first transistor base, a second resistor of low impedance connected between the first transistor emitter and base, a third resistor connected between the grounded terminal and the second transistor base, an electrical load f'or receiving a formed pulse during the circuit low impedance state and connected between the first transistor coliector and the grounded terrninal, a first diode connected between the second transistor emitter and the grounded terminal in forward current conducting relation, a fourth resistor connected between the first transistor emitter and the second transistor emitter for providing a bias current through .the first diode, and a second dio

Description

FIE E4 y 8, 1962 w. M. NELLIS 3,033,998
PULSE FORMER Filed July 13, 1959 FIG. 1
mpu-r VOLTAGE TIME CAP/l c/ronso VOLTAGE 77: I N V EN TOR. Wat/4M Mae raw 4424/:
4 rramvsrs (OUTPUT voume:
United States Pate 3,033,998 PULSE FORMER Wilham Merton Nellis, Maplewood, Miun., assignor to American Monarch Corporation, Minneapolis, Minn., a corporation of Minnesota Filed July 13, 1959, Ser. No. 826,854
2 Claims. (Cl. 307-885) g This invention relates to a bistable electrical circuit for forming an electrical impulse of a predetermined duration in response to a signal of shorter duration.
In digital systems it is often desirable for timing purposes to provide an electrical signal of a predetermined duration which is greater than the pulse width of the signals used in the system. Various types of pulse formers have been utilized to provide such a function including the well known monostable multivibrator in which one of the two non-linear discharge elements therein, such as a transistor, is biased to non-conduction or a high impedance state while the other element is biased to a highly conductive or a low impedance state. The circuit is responsive to an input signal of short duration to switch the conduction or impedance states for a predetermined time, after which the multivibrator automatically reswitches to the initial state. These devices when utilizing a minimum number of circuit components have a tendency to respond to supply voltage changes and noise as well as for a valid input signal. This sensitivity to extraneous electrical disturbances is in part caused by the coupling capacitor in the circuit storing electrical energy in the form of an electrical charge and one of the discharge elements drawing current through the circuit to provide power therein.
This inventionobviates the above objections by providing a pulse former wherein both non-linear discharge elements are in high impedance state and both switch to a low impedance state for a predetermined time in response to an input signal of short duration. The circuit is insensitive to extraneous electrical disturbances and provides rapid impedance switching from both high to low and low to high impedance states.
Accordingly it is an object of this invention to provide a novel pulse former in which both discharge elements are in a normally high impedance state when the pulse duration determining elements are in a de-energized state.
It is another object of this invention to provide a novel pulse former in which both discharge elements are normally in a high impedance state and means are provided for rapidly discharging the pulse duration determining elements charged during a low impedance state after the discharge elements have reswitched to a high impedance state.
It is a further object of this invention to provide a pulse former having both discharge elements therein normally in a high impedance state and in which the formed pulseload is a part of the means rapidly discharging the pulse duration determining elements after the discharge elements have switched to a high impedance state.
It is still another object of this invention to provide a pulse former in which the pulse width determining elements are series connected in an electrical circuit loop having high gain for switching the impedance states of the discharge elements therein.
These and other more detailed and specific objects will be disclosed in the course of the following specification, reference being had to the accompanying drawing, in which- FIG. 1 is a schematic drawing of a circuit embodying this invention.
FIG. 2 illustrates typical wave forms associated with the FIG. 1 circuit.
With reference now to the drawing complementary ing material. With NPN transistor 12 in a high impedance state, i.e., at collector current cutolf, the PNP transistor 10 is also in a high impedance state. The current drive to base 10B is provided from the resistances 14 and 16 formed junction 18 as determined by the impedance state of discharge element12. When element 12 is in a high impedance state it is apparent that the battery B voltage is essentially applied to base 10B as well as emitter or high current electrode 10E providing no current through the base electrode. Resistance 14 of small impedance is primarily provided to reduce the leakage current effect on the bistable circuit.
The base or control electrode 12B is connected to junction 20 between resistances 22 and 24 with resistance 22 being coupled to the transistor or discharge element 10 collector or high current electrode to complete a series connected bistable or latch circuit, as will become apparent. To switch the discharge elements 10 and 12 to a low impedance state a negative going signal 27 of short duration from the source 26 is applied to junction 18 and thus base 10B. The input pulse voltage is developed across resistance 14 to make base 10B negative with respect to emitterjliiE. Base drive current flows through the base electrode 10B making the transistor or element 10 conductive or tending toward a low impedance state as measured between the collector and emitter high current electrodes.
The change in impedance of the element 10 causes the junction 28 voltage to become somewhat positive with respect to the initial voltage thereon. The voltage change is transferred through the timing capacitor 30 and re sistance 22 to the base electrode 12B. The positive going transient voltage just described causes NPN transistor 12 to become slightly conductive tending toward a low impedance state which draws additional current through re; sistance 16 and thereby tending to make the voltage on termed the low impedance state. Upon termination of the pulse 27 the voltage on junction 18 is shown as wave 31 and the circuit remains in the low impedance state providing voltage pulse 32A across the load 32 and having an amplitude near the battery voltage potential.
It is seen that the base drive current for NPN transistor 12 is provided through transistor 10, thence timing capacitor 30 and resistance 22. This small current is operative to charge capacitor 30 while the circuit low impedance elements permit a substantial current to flow through a load 32 from the transistor 10 and battery B. The voltage across the timing capacitor 30 is shown by numeral 33 and when the capacitor is substantially charged as at 35 the base drive current for transistor 12 is decreased below the base current amplitude required for transistor 12 collector current saturation. This action reduces the current through the high current electrodes -12C and 12B and thus permits junction 18 voltage to move more positive to make transistor less conductive. The regenerative loop again provides cumulative impedance switching action in that the positive going transient at junction 18 increases the impedance of transistor 19 causing the voltage at 28 to become less positive further reducing the base drive current to the transistor 12. Since this switching action is very rapid and the capacitor 30 has a charge thereacross as indicated in f circuit to extraneousrelectrical disturbances.
impedance state providing a very sharp turn-oft of pulse 7 The capacitor 30 must now discharge through the load impedance 32 and the series connected resistances 22 and 24. Since this series circuit loop is a'relatively high impedance the discharge time may be greater than the duration of the formed pulse 32A across theload 32. The repetitive frequency at which the circuit can provide the desired pulses is in such a case limited by the discharge time of the capacitor 30.
To increase the repetitive frequency of operation a uni-directional conducting device or diode 36 is connected in parallel with the resistances 22 and 24 with its cathode electrode connected to the capacitor 7 39 to provide a lowered impedance discharge pathfor the capacitor rapidly placingthecapacitor in a discharged state. It is seen that with the two discharge elements in a high impedance state-the voltage across the capacitor 30 urges electrical curr'entto flow through load 32 and thence through diode 36 in the forward direction with the load32 absorbing most of the electric charge. Since the load 32 is preferably of low impedance, for example about 1000 ohms, the discharge time for the capacitor 30 is greatly: reduced as indicated by trailing edge 37 rather than the previous discharge voltage wave 37A through the high impedance resistances 22 and 24.
When the circuit'is in the iow impedance state it is seen the base drive current through resistance 22 causes a voltage drop'thereacross to reverse bias the diode 36 to current cutofi and thus effectively remove it from the circuit.
To aid in rapid'turnotf a silicon diode or uni directional current conducting device 38 with a small forward impedance is connected in the forward current conducting direction between emitter electrode 12B and the battery B negative or grounded terminal. Resistance 40 connected to the battery positiveterminal provides a bias current through diode 38 making the emitter 12E at all times slightly positive with respect to ground potential.
This feature not only aids in driving the transistor 12 to a high impedance state but adds to the insensitivity of the Further circuit insensitivity to the disturbances may be provided by adding a filtercapacitor 42 between the transistor 10' collector electrode and ground. Since the filter 42 has a much larger. capacitive value than timingcapacitor 30,
4 it is ineffective to materially alter thecircuit operation, except to absorb any extraneous electrical. signals. Filter 42 is desirable when load 32 is a relay.
It is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims. Having now therefore fully illustrated and described my invention, what I claim .to be new and desire to protect by Letters Patent is: 7
1. A pnlse former comprising first and second transistors of complementary types, a'supply voltage source having a grounded terminal anda second terminal connected to. the emitter ofthefirst transistor, a signal source for providing a pulse of short duration to the first transistor base for switching the circuit from a high to a low impedance state, a series connected capacitor and resistor connecting the first transistor collector and second transistor base together, a first resistor connecting the second transistor collector to the .first transistor base, a second resistor of low impedance connected between the first transistor emitter and base, a third resistor connected between the grounded terminal and the second transistor base, an electrical load f'or receiving a formed pulse during the circuit low impedance state and connected between the first transistor coliector and the grounded terrninal, a first diode connected between the second transistor emitter and the grounded terminal in forward current conducting relation, a fourth resistor connected between the first transistor emitter and the second transistor emitter for providing a bias current through .the first diode, and a second diode'connected' from the grounded te'rminal to between the series connected capacitor; and
References Cited in the filejof this patent V UNITED srArEs PATENTS 2,770,732 Chong Nov.- 13, 1956 2,837,663 Walz June 3, 1958 2,877,360 Moore Mar. 10,1959 2,927,268 Haggai et al Mar. 1,1960
7 OTHER REFERENCES A publication put out by Sylvania Electric Products Inc called Sylvania Transistor News- (SD2100M- 559) date Miay l959, relying on the Blinker Light" circuit shown therein. r
US826854A 1959-07-13 1959-07-13 Pulse former Expired - Lifetime US3033998A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US826854A US3033998A (en) 1959-07-13 1959-07-13 Pulse former

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US826854A US3033998A (en) 1959-07-13 1959-07-13 Pulse former

Publications (1)

Publication Number Publication Date
US3033998A true US3033998A (en) 1962-05-08

Family

ID=25247700

Family Applications (1)

Application Number Title Priority Date Filing Date
US826854A Expired - Lifetime US3033998A (en) 1959-07-13 1959-07-13 Pulse former

Country Status (1)

Country Link
US (1) US3033998A (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3215852A (en) * 1960-06-29 1965-11-02 Ibm Monostable transistor trigger having both transistors normally biased in the non-conducting state
US3222539A (en) * 1960-03-04 1965-12-07 Western Electric Co Trigger circuit
US3227891A (en) * 1959-09-30 1966-01-04 North America Aviat Inc Timing pulse generator
US3244906A (en) * 1962-12-04 1966-04-05 North American Aviation Inc Transistor monostable multivibrator circuit
US3292005A (en) * 1963-09-23 1966-12-13 Honeywell Inc High-resolution switching circuit
US3293454A (en) * 1964-03-16 1966-12-20 Bendix Corp Indicator lamp control circuit employing charge-controlled timing capacitor coupling cascaded transistors
US3406287A (en) * 1963-06-26 1968-10-15 Bendix Corp Radiation sensitive device for detecting sun in a selected field of view
US3458732A (en) * 1967-03-15 1969-07-29 Honeywell Inc Latching type switching circuit
US4053790A (en) * 1976-08-31 1977-10-11 Heath Company Power line switch with time delay turn off
US4916432A (en) * 1987-10-21 1990-04-10 Pittway Corporation Smoke and fire detection system communication

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770732A (en) * 1955-07-08 1956-11-13 Rca Corp Transistor multivibrator circuit
US2837663A (en) * 1956-05-16 1958-06-03 Gen Dynamics Corp Monostable trigger circuit
US2877360A (en) * 1956-06-06 1959-03-10 Jimmy J Moore Triggered transistor oscillator circuit to replace a sensitive d. c. relay
US2927268A (en) * 1957-11-01 1960-03-01 Rca Corp Tachometer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770732A (en) * 1955-07-08 1956-11-13 Rca Corp Transistor multivibrator circuit
US2837663A (en) * 1956-05-16 1958-06-03 Gen Dynamics Corp Monostable trigger circuit
US2877360A (en) * 1956-06-06 1959-03-10 Jimmy J Moore Triggered transistor oscillator circuit to replace a sensitive d. c. relay
US2927268A (en) * 1957-11-01 1960-03-01 Rca Corp Tachometer

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3227891A (en) * 1959-09-30 1966-01-04 North America Aviat Inc Timing pulse generator
US3222539A (en) * 1960-03-04 1965-12-07 Western Electric Co Trigger circuit
US3215852A (en) * 1960-06-29 1965-11-02 Ibm Monostable transistor trigger having both transistors normally biased in the non-conducting state
US3244906A (en) * 1962-12-04 1966-04-05 North American Aviation Inc Transistor monostable multivibrator circuit
US3406287A (en) * 1963-06-26 1968-10-15 Bendix Corp Radiation sensitive device for detecting sun in a selected field of view
US3292005A (en) * 1963-09-23 1966-12-13 Honeywell Inc High-resolution switching circuit
US3293454A (en) * 1964-03-16 1966-12-20 Bendix Corp Indicator lamp control circuit employing charge-controlled timing capacitor coupling cascaded transistors
US3458732A (en) * 1967-03-15 1969-07-29 Honeywell Inc Latching type switching circuit
US4053790A (en) * 1976-08-31 1977-10-11 Heath Company Power line switch with time delay turn off
US4916432A (en) * 1987-10-21 1990-04-10 Pittway Corporation Smoke and fire detection system communication

Similar Documents

Publication Publication Date Title
US2831113A (en) Transistor relaxation circuits
US2845548A (en) Static time delay circuit
US2906888A (en) Electrical counting circuits
US3508167A (en) Pulse generator
US3033998A (en) Pulse former
US2891172A (en) Switching circuits employing junction transistors
US4092551A (en) A.C. powered speed up circuit
US3121802A (en) Multivibrator circuit employing transistors of complementary types
GB1030479A (en) A detector of pulses exceeding a predetermined length
US3433978A (en) Low output impedance majority logic inverting circuit
US3114049A (en) Transistor trigger circuit
US3735154A (en) Disabling circuit having a predetermined disabling interval
US3292005A (en) High-resolution switching circuit
US3711729A (en) Monostable multivibrator having output pulses dependent upon input pulse widths
US2644894A (en) Monostable transistor circuits
US3142025A (en) Astable to bistable multivibrator control circuit
US2937291A (en) Single shot bistable circuit
US2965770A (en) Linear wave generator
US3008088A (en) Synchronized multivibrator with selectable clamping means for rendering it inoperative
US3496389A (en) Timing circuit with field effect transistor
US3015784A (en) Sawtooth oscillator
US3391286A (en) High frequency pulseformer
US3448296A (en) Apparatus for stretching pulses exceeding predetermined amplitude
US3654494A (en) Capacitor type timing circuit utilizing energized voltage comparator
US3980901A (en) Trigger pulse generator circuit